Add multiarch build to workflow

.github/workflows/build.yaml

@@ -9,15 +9,20 @@ jobs:
   docker:
     runs-on: ubuntu-20.04
 
+    env:
+      PLATFORMS: linux/amd64,linux/386,linux/arm64,linux/arm/v7
+
     steps:
       - uses: actions/checkout@v2
 
-      - name: Log into GitHub Container Registry
-        uses: docker/login-action@v1
-        with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Install script dependencies
+        run: pip3 install -r scripts/requirements.txt
 
       - id: vars
         name: Generate build vars
@@ -26,7 +31,10 @@ jobs:
           echo "::set-output name=tag::"${SHA:0:8}-$(date +%s)Z""
 
       - name: Build
-        run: make PLUGIN_TAG=${{ steps.vars.outputs.tag }} plugin
+        run: make PLUGIN_TAG=${{ steps.vars.outputs.tag }} multiarch
 
       - name: Push
-        run: make PLUGIN_TAG=${{ steps.vars.outputs.tag }} push
+        env:
+          REGISTRY_USERNAME: ${{ github.actor }}
+          REGISTRY_PASSWORD: ${{ secrets.GITHUB_TOKEN }}
+        run: make PLUGIN_TAG=${{ steps.vars.outputs.tag }} push-multiarch